This project focuses on disease states affect chemosensory epithelia. We turn our attention herein to two diseases-on involving taste, the other smell-possibly attributable to disturbances in the sensory epithelium: 1) radiation induced dysgeusia and 2) steroid dependent anosmia. We will utilize contemporary psychophysical, anatomical and physiological tests to examine the function and structure of the epithelium in control subjects and in the appropriate patient populations. This multidisciplinary approach will allow us to provide a more complete description of the functional and structural changes that correlate with sensory disturbances. Subjects diagnosed with squamous cell carcinoma of the head or neck will be tested for gustatory function prior to, during and after radiation treatment. Quantitative and qualitative taste changes will be tracked throughout the time period of loss and recovery of function. Vital staining of the tongue will allow us to measure taste pore density. Biopsies of fungiform papillae will permit us to measure taste bud integrity and function by means of the markers gustducin and cytokeratin- 19. In order to allow comparison between psychophysical and anatomical observations, all measures will be performed on the same area of the anterior dorsal surface of the tongue. Likewise, we will test subjects with allergic rhinitis for olfactory function prior to, during and after topical steroid treatment. Both detection ability and supra-threshold intensity perception will be determined unilaterally. Two biopsies of the olfactory epithelium will be analyzed using three histochemical markers: olfactory marker protein (OMP) and GAP43 as measures of cell maturity, and glucocorticoid receptor (GR) to determine changes in GR distribution. Parallel changes in membrane current and intracellular calcium induced by stimulation with odors will be measured in isolated olfactory receptor neurons using loose patch recording by stimulation with odors will be measured in isolated olfactory receptor neurons using loose patch recording with simultaneous calcium imaging. In addition, in order to assess possible changes in mucus ion homeostasis in this disease state, we will determine mucus ion content by flame photometry and ratio-imaging of ion-specific dyes.